1. Field
The presently disclosed embodiment relates to a medical device for introducing a therapeutic substance into a body, particularly to a medical device to be used for operation using a catheter.
2. Brief Description of Related Developments
In a therapeutic method for introducing a therapeutic substance into a body, vascular embolization, for example, arterial embolization for treatment of hepatocellular carcinoma and the like has been used. In such treatment, in order to cut off feeding of nutrition to cancer cells, a blood vessel is clogged with an intravascular embolization substance to kill the cancer cells.
Introduction of such a therapeutic substance into a body cavity is performed by connecting a feeding member such as a syringe for feeding a therapeutic substance containing the therapeutic substance including an intravascular embolization substance with a catheter hub, and inserting the catheter in the blood vessel up to a vicinity of an affected part. The syringe and the catheter hub are generally connected by luer taper connection, and the syringe is inserted into the catheter hub to be fitted and fixed. As shown in FIG. 7, the end portion of the syringe at the distal end side generally has an end face 101 facing an axial direction of the syringe 100, and the syringe is connected to the catheter hub such that a flow channel 103 at the end portion of the syringe at the distal end side is separated front an inner surface of the catheter hub 102. Therefore, it results in an annular dead space D lateral to the flow channel 103 with respect to an axial direction of the syringe 100 as a space between the end face 101 of the syringe 100 and the inner surface of the catheter hub 102. As shown in FIG. 7, such a dead space D is generated by a step formed along the flow channel between the end face 101 of the syringe 100 and the tapered surface of the catheter hub 102. This step causes a problem in which the therapeutic substance such as an intravascular embolization substance remains in the dead space B due to generation of turbulence in the dead space D of a flow path of the therapeutic substance when injecting the therapeutic substance from the syringe 100. Further, this remaining therapeutic substance in the dead space D causes a problem such that the therapeutic substance is administrated to a patient only in an amount smaller than a predetermined amount required for the treatment; the remaining therapeutic substance is flowed into a body cavity at once to temporarily increase the concentration more than a predetermined value; the remaining therapeutic substance flows into a body cavity in the following operation and is delivered to a portion other than the originally targeted port ion; and an excess amount of therapeutic substance is required for the purpose of administrating to a patient a predetermined amount necessary for the treatment.
From the viewpoint of the mentioned problems, in a system for administration of a therapeutic substance into a body cavity including administration of a therapeutic substance comprising an intravascular embolization substance into an affected part for cancer treatment, various attempts have been performed in order to eliminate a dead space resulting from luer taper connection. For example, in Japanese Patent No. 2002-503991, there is disclosed a syringe 200 having, at its distal end, a tapered outer wall adapted to an inner wall shape of a micro catheter luer hub 201. In Japanese Patent No. 4357067, there is disclosed, as shown in FIG. 9, a structure where a gap in a connected portion 301 is filled with a filling body 303 when a male adapter 302 is fitted into the connected portion 301 being a female adapter of a connector 300. This filling body 303 is formed from a material being excellent in flexibility and cushioning properties such as a soft synthetic resin or a silicone rubber, and is configured so that the male adapter 302 is connectable even in the case of the distal end of the male adapter 302 is extended.